(bison.info) Glossary

 
 Glossary
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 Backus-Naur Form (BNF)
      Formal method of specifying context-free grammars.  BNF was first
      used in the `ALGOL-60' report, 1963.   Languages and
      Context-Free Grammars Language and Grammar.
 
 Context-free grammars
      Grammars specified as rules that can be applied regardless of
      context.  Thus, if there is a rule which says that an integer can
      be used as an expression, integers are allowed _anywhere_ an
      expression is permitted.   Languages and Context-Free
      Grammars Language and Grammar.
 
 Dynamic allocation
      Allocation of memory that occurs during execution, rather than at
      compile time or on entry to a function.
 
 Empty string
      Analogous to the empty set in set theory, the empty string is a
      character string of length zero.
 
 Finite-state stack machine
      A "machine" that has discrete states in which it is said to exist
      at each instant in time.  As input to the machine is processed, the
      machine moves from state to state as specified by the logic of the
      machine.  In the case of the parser, the input is the language
      being parsed, and the states correspond to various stages in the
      grammar rules.   The Bison Parser Algorithm Algorithm.
 
 Grouping
      A language construct that is (in general) grammatically divisible;
      for example, `expression' or `declaration' in C.   Languages
      and Context-Free Grammars Language and Grammar.
 
 Infix operator
      An arithmetic operator that is placed between the operands on
      which it performs some operation.
 
 Input stream
      A continuous flow of data between devices or programs.
 
 Language construct
      One of the typical usage schemas of the language.  For example,
      one of the constructs of the C language is the `if' statement.
       Languages and Context-Free Grammars Language and Grammar.
 
 Left associativity
      Operators having left associativity are analyzed from left to
      right: `a+b+c' first computes `a+b' and then combines with `c'.
       Operator Precedence Precedence.
 
 Left recursion
      A rule whose result symbol is also its first component symbol; for
      example, `expseq1 : expseq1 ',' exp;'.   Recursive Rules
      Recursion.
 
 Left-to-right parsing
      Parsing a sentence of a language by analyzing it token by token
      from left to right.   The Bison Parser Algorithm Algorithm.
 
 Lexical analyzer (scanner)
      A function that reads an input stream and returns tokens one by
      one.   The Lexical Analyzer Function `yylex' Lexical.
 
 Lexical tie-in
      A flag, set by actions in the grammar rules, which alters the way
      tokens are parsed.   Lexical Tie-ins.
 
 Literal string token
      A token which constists of two or more fixed characters.  
      Symbols.
 
 Look-ahead token
      A token already read but not yet shifted.   Look-Ahead
      Tokens Look-Ahead.
 
 LALR(1)
      The class of context-free grammars that Bison (like most other
      parser generators) can handle; a subset of LR(1).  
      Mysterious Reduce/Reduce Conflicts Mystery Conflicts.
 
 LR(1)
      The class of context-free grammars in which at most one token of
      look-ahead is needed to disambiguate the parsing of any piece of
      input.
 
 Nonterminal symbol
      A grammar symbol standing for a grammatical construct that can be
      expressed through rules in terms of smaller constructs; in other
      words, a construct that is not a token.   Symbols.
 
 Parse error
      An error encountered during parsing of an input stream due to
      invalid syntax.   Error Recovery.
 
 Parser
      A function that recognizes valid sentences of a language by
      analyzing the syntax structure of a set of tokens passed to it
      from a lexical analyzer.
 
 Postfix operator
      An arithmetic operator that is placed after the operands upon
      which it performs some operation.
 
 Reduction
      Replacing a string of nonterminals and/or terminals with a single
      nonterminal, according to a grammar rule.   The Bison Parser
      Algorithm Algorithm.
 
 Reentrant
      A reentrant subprogram is a subprogram which can be in invoked any
      number of times in parallel, without interference between the
      various invocations.   A Pure (Reentrant) Parser Pure Decl.
 
 Reverse polish notation
      A language in which all operators are postfix operators.
 
 Right recursion
      A rule whose result symbol is also its last component symbol; for
      example, `expseq1: exp ',' expseq1;'.   Recursive Rules
      Recursion.
 
 Semantics
      In computer languages, the semantics are specified by the actions
      taken for each instance of the language, i.e., the meaning of each
      statement.   Defining Language Semantics Semantics.
 
 Shift
      A parser is said to shift when it makes the choice of analyzing
      further input from the stream rather than reducing immediately some
      already-recognized rule.   The Bison Parser Algorithm
      Algorithm.
 
 Single-character literal
      A single character that is recognized and interpreted as is.
       From Formal Rules to Bison Input Grammar in Bison.
 
 Start symbol
      The nonterminal symbol that stands for a complete valid utterance
      in the language being parsed.  The start symbol is usually listed
      as the first nonterminal symbol in a language specification.
       The Start-Symbol Start Decl.
 
 Symbol table
      A data structure where symbol names and associated data are stored
      during parsing to allow for recognition and use of existing
      information in repeated uses of a symbol.   Multi-function
      Calc.
 
 Token
      A basic, grammatically indivisible unit of a language.  The symbol
      that describes a token in the grammar is a terminal symbol.  The
      input of the Bison parser is a stream of tokens which comes from
      the lexical analyzer.   Symbols.
 
 Terminal symbol
      A grammar symbol that has no rules in the grammar and therefore is
      grammatically indivisible.  The piece of text it represents is a
      token.   Languages and Context-Free Grammars Language and
      Grammar.
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